Patients with HIV infection commonly present with deficits in concentration, attention, reaction times, and short-term working memory. Functional magnetic resonance imaging (fMRI) is a nearly ideal technique to study these deficits because it allows the non-invasive observation of brain activation in real-time. However, high intrinsic levels of acoustic noise during fMRI are a concern because acoustic noise can produce spurious activation or alter the fMRI signals. Acoustic noise interference may also be expected to have differential effects in healthy control subjects and patients with cognitive impairments. Therefore, the specific aims of the project are: 1) to investigate the effect of acoustic noise on fMRI activation in seronegative control subjects, as a function of gender, and 2) to determine the effect of acoustic noise on fMRI studies of working memory and visual attention, in patients with HIV. Our specific hypotheses are 1) in control subjects, fMRI-acoustic noise will increase brain activation in the attentional network (rationale: there will be neural compensation for acoustic noise interference); 2) this effect will be larger in women than in men (rationale: woman are more sensitive to auditory stimuli than men); and 3) increased brain activation in the attentional network will be greater in seropositive men than in seronegative men (interaction between the acoustic noise and HIV status). fMRI will be performed at two different sound pressure levels (at 4 Tesla field) while subjects perform a battery of working memory and visual attention tasks designed specifically to detect abnormalities in patients with HIV. This will make it possible to determine how fMRI-acoustic noise affects brain activation, both in healthy subjects and in HIV patients. The knowledge gained from this study will make it possible to quantify the effect of acoustic noise on fMRI studies of brain injury in patients with HIV. If our hypotheses prove to be correct, the results of this one-year study would allow us to further investigate the effects of acoustic noise on attention in HIV patients who abuse drugs, in a future R01 project. More generally, this study will also improve the understanding of the neural effects of acoustic noise interference during fMRI studies in healthy populations.